Mosquito swarms bring ‘triple whammy’ of infectious disease to Timor-Leste

It is harder to protect against Aedes aegypti mosquitos because they are active all day and night – MARVIN RECINOS/AFP

A triple outbreak of dengue, chikungunya and Zika is threatening an island just an hour’s flight from Australia in what experts warn is a “wake-up call” of the dangers of climate change.

Timor-Leste, bordering Indonesia, has seen its mosquito population spiral out of control as wet and warm weather provides the perfect breeding ground for diseases spread by the insect.

Amid the surge, Timor-Leste recorded its first ever chikungunya outbreak, a condition causing debilitating joint pain with no vaccination or treatment, on record.

Outbreaks of dengue have also been registered, with 147 total cases as of January, as well as Zika, which causes birth defects.

Experts told the Telegraph that the triple outbreak reflects the glaring risks associated with climate change, which will extend the wet and warm mosq uito breeding season.

“Having three outbreaks is a wake-up call, in that sense to say these diseases are coming as the world warms,” said Dr Michael Bonsall, a Professor in the Department of Biology at the University of Oxford.

“In Timor-Leste, the outbreaks are related to important seasonal fluctuations. Climate change will continue to make these sorts of things worse.”

Experts warn the outbreaks in Timor-Leste are a ‘wake-up call’ to the dangers of climate change – Sean Atkins/MAF

Zika hit the headlines as it swept through South America in 2015 and 2016, causing clusters of microcephaly and other neurological disorders in babies.

Though cases have since declined, approximately 40,230 infections were recorded in 2022 – a figure experts fear could rise as temperatures climb.

Dengue, which causes severe headaches, joint pain and rashes, can become increasingly serious if a person is exposed more than once.

Like chikungunya, there is currently no vaccination for Zika and not one widely available for dengue.

A total of 183 cases of dengue from five municipalities have been detected so far.

The capital, Dili, and the neighbouring Ermera municipality are the hardest hit, accounting for nearly 90 per cent of all cases.

A Zika virus infection has also been reported in the Ermera municipality, raising fears of potential further spread.

According to Dr Bonsall, the mix of the three diseases could represent a “serious outbreak” that is difficult to control and will worsen as the wet and warm season continues.

The species of mosquito spreading the infections also complicates matters, he added.

“Aedes mosquitoes that spread these viruses are not like the Anopheles mosquitoes that spread malaria,” he said.

“Anopheles mosquitoes fly around in the night, so you can sleep under a net. But these mosquitoes are around all day. It makes it harder to protect against them.

“Because of this and a lack of vaccinations, there isn’t a single bullet solution.”

The outbreaks recorded in Timor-Leste represent the increasing threat of mosquito-borne diseases worldwide, Trudie Lang, a professor of Global Health Research at the University of Oxford, told the Telegraph.

Heat waves and flooding have allowed invasive mosquitoes to establish themselves further north in recent years.

In 2022, Europe saw more cases of locally acquired dengue than the total number of cases in the previous decade.

Usually, dengue, chikungunya and Zika are largely poverty-related, leaving the world’s most vulnerable populations at risk.

“They’re largely associated with poor housing and places where mosquitoes can breed easily, like stagnant water,” Professor Lang said, describing the outbreak as “very concerning”.

Because developing countries are often the worst hit, there is a lack of research on such outbreaks, leaving the potential dangers unknown, she added.

“There’s often very little surveillance and monitoring going on in many of the worst-affected places in the world,” she said.

“So suddenly we’re restruck with new disease outbreaks without a really good understanding of what’s happening.”

Professor Lang said that lessons learned in the pandemic – mainly that diseases can quickly adapt and spread – should be translated to outbreaks like the one in Timor-Leste.

“They do adapt and change, sometimes they can get more serious or have a different transmission pattern,” she said. “It’s a major public health concern. The world must pay attention.”

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